Thread-chain severing device for sewing machines



Aug. 5, 1952 J. P. ENOS THREAD-CHAIN SEVERING DEVICE FOR SEWING MACHINES 2 SHEETSSHEET 1 Filed Oct. 22 1947 ATme/VEV J. P. ENOS 2,605,729

THREAD-CHAIN SEVERING DEVICE FOR SEWING MACHINES 2 sl-xEE'rs-sr mm 2 Aug; 5, 1952 Filed Oct. 22, 1947 Patented Aug. 5, 1952 UNITED sTATEs PATENT. OFFICE John lll Enos, Union, N. J., assignor .toThe, Singer- .Manufacturing Company, Elizabeth,v J a corporation of New Jersey Application October 22, 1947. Serial No. 781,365.

This invention relates to devices for severin thread-chains extending from stitched articles and is in the nature of an improvement in, the thread-severing device of my prior United States Patent No. 2,318,843; May 11, 1943.

The present invention has for its primary object to reduce to a minimum the possibility of marring the work, or the stitches formed inthe work, by the compler'nental thread-chain severing elements,

Another object of this invention is to increase the efliciency of the thread-chain severing device in cases wherein the stitched work isdeflected out of the line of scam formation.

With these and other objects in view, as will hereinafter appear, the invention consists in the devices, combinationsand arrangements of parts described in the accompanying drawings of a preferred embodiment of the invention and in which:

Fig. 1 is a frontend elevation, partly in section,

of a portion of a sewing machine containingv the improved thread-severing device.

Fig. 2 is a right hand side elevation of the thread-severing device, the'neeclIe and presser bars being broken away and the throat-plate of the machine being shown in section. i

Fig. 3 is'a top plan view of the thread-severing device, with the needle and presser bars shown in section. 1

Fig. 4 is a bottom plan view of the threadsevering device.

Fig, .5 is afrear end elevation of the severing device, with the throat-plate. of the machine shown in section. y

Fig. 6 is a top plan-view of a portion of the cloth-plate and including the throat-plate and feed-dogof the machine, l l c Fig. 7 represents. a longitudinal vertical section of the thread-severingdevice. f

Referring to the drawings, the sewing machine containingthe. 1 present 1 improvement has: the usual frame inc1uding-=a;':.workrsupporting bedplate I and a bracket-arm head 2. Journaled for endwise reciprocation-pin the-head 2 is a vertically disposed needle-bar 3 carrying an eyepointed needle 4. Complemental to the needle 4 in theformation'of lock-stitches is a loop ta'ker which, in the present case, is in the form of a horizontal-axis rotary hook'adapted to cast loops of needle-thread about a mass of under thread contained in a thread-carrier '6 suitably journaled in the rotary hook and restrained'against rotation therewith. The present invention, however, is not limited to any particular-form 0f stitchforming mechanism,

10, Claims. (01. 11'2 252)" The work; W (shown in section Fig. 7) is intermittently advanced past the needle! by a feed-dog I of the drop-feed, type. The feed-dog I issecured by screws 8 upon a horizontally disposed feed-bar 9, of which the rearward end is pivotally connected to the upper end of a vertically disposed rocker I0 carried by a feed-advance rock-shaft II which may be supported and actuated in any usual or suitable manner to impart work-advancing movements of variable amplitude to the feed-dog ,l. -At it forward end, the feed-bar 9 hasaforkIZ operatively} connected to a crank-arm of theusualfeed-lift rock-shaft I4. The. present invention -however, is not lim ited to any particular form; of feed-dog actuating mechanism. y

The feed-dog I and I6 which are preferably equal in length, a relativelyshort intermediate row of teeth I! disposed in front of the needle path andin the line ofseamformation, and another intermediate row of teeth I8- disposed rearwardly of the needle path and also in the line of seam formation. The rear row of teeth I8 o1 the feed-dog extends rearwardly beyond the outer rows of teeth I5 and I6, and terminates in a thread-severing member I9. Thethread severing member I9 has a horizontally flattened. upper face disposed in a plane containing the work-engaging edges of the several rows of feededog teeth; said member I9 beingywidened crosswise of the line of seam formation and at opposite sides of the row of teeth I8 so that the oppositeside faces of the member I9 are, disposed in the planes containing the outer side faces of the outerrows of teeth I5 and I6. The upper'rear edge of the feed-dog member I9, which is substantially normal to theline of feed, is formed as a sharpened cutting edge I9 by hoilcwgrinding the. rear end; portion Ziiof said member.

In its operative:- wbrkadvjancing movements, the feed-dog I is projected through a slotted throat-plate .2Iwhich is secured by screws 22 upcnth'e bed-plate IL' The throat-plate 2| is cut awayto. provide parallel outer slots 23 and 24 for the rows I5 and, I6zof feed-dog teeth, a front intermediate slot 25' for the feed-dog teeth I1, and a rear intermediate slot 26' for the feed-dog teeth I8. The throat-plateas thus cut away is provided with spaced front parallel bars 21 which are connected by a land 28 with the spaced rear parallel bars 29; the. land 28 containing a needleaperture 3B. At their rearward ends, the bars 29 of the throat-plate terminate in front of the thread-severing memberi9 and are anchored to has two outer rows of teeth i5 the throat-plate by oppositely directed and alined ribs 3|. The throat-plate 2| is cut away rearwardly of the ribs 3| to provide a wide slot 32 for the thread-severing member IS; the slot 32 being elongated sufficiently to aiford clearance rearwardly of the thread-severing member I9 to permit severed thread particles to drop down through the throat-plate.

Opposed to the feed-dog I is presser-foot 33 having an upper shank-portion 34 secured by a screw 35 to the lower end of the usual springg provided in the upper face of the lever 52. By angular adjustment of the stud 56, the eccentricdepressed presser-bar 36 journaled for endwise;

vertical movement in the bracket-arm head.2. A forwardly offset lower portion-31 of the presserfoot shank is provided with a guideway 38 for a vertically movable T-shaped supporting bar 39, of which the divergent arms overlie a shoul- T v der 46 formed by offsetting the lower portion3l. V

3. The lever 58 performs endwise sliding as well as pivotal movements in the bracket-slot BI and, in order to lubricate the lever 58, a piece of suitable lubricant absorbent material 68 is secured by a screw 69 in the slot 59 above the lever 58.

The lever 52 is held in engagement with the roller 55 of-thestud 56 by means of a coil-spring I embracing a post H depending from a lug 120i the bracket 62; the spring having its upper end disposed in an aperture in the lug l2 and having its lower end seated in an aperture portion 56 thereof may be turned to vary the lowest position of the cutter-block 53 carried by the lever '52.

of the presser-foot shank. Hinged to thelo'wer end of the supporting bar 39, by a transverse pivotepin-M is a:work engaging sole-plate 42 having an upturned toe 43 formed with a slot 44 terminating at its inner endin a needle-clearance opening 45.- Engaging and bearing downwardly upon the divergent upper arms of the T-shaped supporting bar'39 are the ends of a spring 46 securedby' a'screw 41 upon the upper shank-portion 34 of the presser-foot, whereby the sole pla'te 42is'yieldingly depressed to an extent limited by the engagement of the arms of the supporting bar39 with theshoulder 40.

The lower shank-portionfljof the presser-foot terminates in'a work-engaging face 48 disposed rearwardly ofthe 'soleplate 42; the shank-portion 31 being suitably recessed at its lower front side to afford the requisite clearance for the heel of the sole-plate 42. v At its rearward side and medianly of thewidth thereof, the shankportion 31 is formed witha relatively narrow extension-piece 49 providing 'a continuation of the work-engaging face 48. The work-engaging face 48 and the continuation thereof in the extension-piece 49 are formed with a groove 50 in alinement with 'the line of seam formation and functioning to guide the thread-chain T whic connects stitched articles.

Pivotally connected 'to the shank-portion 31 of the presser-foot by a pivot-pin 5| disposed horizontally crosswise of the line of'seam formation, is'a carrier-arm 52 extending rearwardly from the presser foot. Suitably secured upon the carrier-arm 52 is a cutter-block 53 which is recessed in its lower front face to provide clearance for the extension-piece 450i the presserfoot and to form, in the lower face of the cutterblock 53, a cuttingedge' 54. The cutting-edge 54 extends across the line of'seam formation and is disposed in close proximity to the rearward end of the extension-piece 49 of the presser-foot,

whereby the cutting-edge 54 is traversed by the'- cutting-edge IQ of the feed-dog in its work-advancing'movements. V

The carrier-arm 52 isbent to overlie a roller 55 carried by an eccentric-portion 56 of a shouldered stud 565 secured by a nut 51 upon the rearward end of an actuating lever 58; Intermediate its ends, the lever 58 is lengthwise provided with a slot 59, through which extends a fulcrumscrew 66 spanning a lever-confining slot 6| formed vertically in a bracket 62' secured by a screw 63 to the upper portion 34 of the presserfoot shank. The apertured forward end of the lever 58 is entered by a roller 64 carried by a stud-screw 65 threaded into a block 66 secured by screws 61 upon the lower end of the needle-bar In the operation of the machine, the vertically reciprocating needle-bar 3 actuates the lever 58, thereby rocking the carrier-arm 52 and automatically raising and lowering the cutter-block 53; the latter reaching its lowest position determined by the roller 55-of the stud 56 when the needle-' bar reaches the upper end of its stroke. The

cutting-edge 54 of the cutter-block 53 is thereby momentarily lowered at the proper time, in the absence of work-plies under the cutter-block, to position the cutting-edge 54 for thread-shearing cooperation with "the cutting-edge I9 of the feed-dog. From this it will be understood that during the major portion of the normal stitch forming cycle, the cutter-block 53 is lifted to an extent which reduces to a minimum the ,possibility of marring stitches formed in the workplies. However, as soon as the finishing ends of the stitched work-plies pass the; cutter-block 53,

the latter will .be momentarily lowered in each stitch-forming cycle into a position wherebythe thread-chain extending from the, work-plies will be promptly'severed close to the work and ate point spaced from the :needle-path a suificient distance to provide the necessary length ,of

thread for beginning the next stitching operation.

While the thread-chain formed in the absence of work is-normally guided by the presser-foot 50 in the line 'of feed, some operators have a tendency to pull the stitched work away from the line of feed. The present construction provides for that contingency by forming the lower thread-severing member so as to extend the, full width of the feed-dog. This is permitted by the special "throat-plate construction hereinbefore described and which includes the supporting ribs for the throat-plate bars 29.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a sewing machine, stitch-forming mechanism including a 'reciprocatory needle bar, a

needle carried thereby, a work-support, a feed-' dog operating through "saidwork-support for advancing work across the path of needle-reciprocation, a primary thread-'chainsevering memv stitch-forming cycle for moving said comple--- mental severing member into and out of engage- A ment with the work being stitched.

2. In asewing machine, a work-support, stitchforming mechanism including a reciprocatory needle bar, a needle carried thereby, a primary thread-severing member having 'efiective threadsevering movements in the direction of movement of stitched work through the machine, means for actuating said member, a complemental threadsevering member disposed rearwardly of said needle and movable in the absence of work into position for coaction with said primary severing member for severing the stitching thread extending from said needle, said members being, movable into thread-shearing relation from. opposite sides of the plane of the work,-and automatically act ing means including said needle-bar for moving said complemental severing member out of engagement with the work being each stitch-forming cycle. A

3. Ina sewing machine, stitch-forming mechanism including a reciprocatory needle bar, a needle carried thereby, a work-support, a feed-dog operating through said work-support, a presserfoot opposed to said feed-dog and movable toward and from said work-support, a primary threadchain severing member carried by said feed-dog,

a bracket supported for movement with said presser-foot, a carrier-arm pivotally mounted on said bracket, a complemental thread-chain severing member supported by said carrier-arm and movable into position for thread-shearin coaction with said primary severing member, and means including a lever mounted on said bracket and connected to said needle-bar and carrier-arm for actuatingv said carrier-arm in each stitch-forming cycle for intermittently moving said complemental severing member toward and from said work-support.

4. In a sewing machine, a work-support, stitchforming mechanism including a reciprocatory needle-bar, a primary thread-severing member having effective thread-severing movements in the direction of movement of stitched work through the machine, means for actuating said member, a complemental thread-severing member disposed rearwardly of said needle and movable in the absence of work into position for coaction with said primary severing member, yielding means biasing said complemental thread-severing member toward thread-severing position, and needle-bar operated means i for intermittently moving said complemental severing member away from said work-support.

5. In a sewing machine, a work-support, stitchforming mechanism including a reciprocatory needle bar, a needle carried thereby, a primary thread-severing member having effective threadsevering movements in the direction of movement of stitched Work through the machine, means for actuating said member, a complemental threadsevering member disposed rearwardly of said needle and movable in the absence of work into position for coaction with said primary severing member, said members being movable into thread-shearing relation from opposite sides of said work-support, yielding means biasing said stitched; during 7 means actuated bysaid-lever-and efiec'tive in each stitch-forming cycle formoying the spring biased complemental severing member out" of engage-' mentwith'the-work being s'titched. I r

7; In a sewing machine, awork-support stitchforming meehanism' including a"'.reci procatory needle-bar, primary and complemental thread- 7 chain severingmembers operabl'e toward and from each other from-opposite sides'oi said worksupport-and intermittently brought into threadchain shearing relationship with each other in the absence of work therebetween, means for actuating said primary severing member, a carrier-arm for said complemental thread-severing member, and means including an operative connection with said needle-bar for actuating said carrier-arm to move said complemental severing member yieldingly toward and positively away from said work-support.

8. In a sewing machine, stitch-forming mechanism including a reciprocatory needle-bar, a work-support, a work-advancing feed-dog operating through said work-support, a primary thread-chain severing member carried by said feed-dog, a presser-foot opposed to said feeddog, a carrier-arm pivotally mounted upon said presser-foot, a complemental thread-chain severing member mounted upon said carrier-arm and disposed rearwardly of said presser-foot to extend across the line of scam formation, a supporting bracket, a lever fulcrumed upon said bracket and operatively connected to said needlebar for actuation thereby, an adjustable eccentric-stud carried by said lever in position for engagement by said carrier-arm, and a spring yieldingly biasing said carrier-arm into engagement with said stud.

9. In a sewing machine, stitch-forming mechanism including a reciprocatory needle, a worksupport including a throat-plate provided with a needle-aperture, said throat-plate being cut away to form a plurality of feed-slots including parallel outer rows of feed-slots and an intermediate feed-slot disposed between said outer rows of slots rearwardly of said needle-aperture in the line of seam formation, said intermediate slot being separated from said outer slots by parallel throat-plate bars terminating at their rearward ends in divergent ribs closing the rearward ends of said outer slots on a line substantially normal to the line of feed, and said intermediate slot terminating in a thread-severing member slot disposed rearwardly of said ribs and having its side edges in substantial alinement with the outer edges of said outer feed-slots, a work-advancing feed-dog having outer and intermediate rows of teeth operating through said feed-slots of the throat-plate, the intermediate row of teeth of the feed-dog terminating in a primary thread-severing member provided with a cutting edge substantially equal in width to said thread-severing member slot of the throatplate, a presser-foot opposed to said feed-dog, a complemental thread-severing member mounted on sai presser-foot and means yieldingly depressing said complemental thread-severing mem ber toward said throat-plate.

10. In a sewing machine, a horizontal worksupport, stitch-forming mechanism including a needle and means for reciprocating'said needle, primary and complemental thread-chain severing members operable'toward and from each other-from opposite sides of said work-support and intermittently brought into thread-chain shearing relationship with each other in the absence of work therebetween, .means'located at the-under side of said work-support for positively reciprocating said primary thread-severing member back and forth relative to said work-support, a crank located at the upper side of said worksupport andconnected for actuation by saidneedle-reciprocating means, and means including operative connections between said crankand 7' severing member into andvout of contact with the work being stitched and into and out of contact with said primary thread-severing member in the absence of work therebetween.

JOHN P. ENOS.

REFERENCES CITED The following references are of record in the 10 file of this 'patent: r

v UNITED STATES PAT NTS Number Name Date i 1,765,342 Lutz June 17, 1930 2,293,236 Anderson Aug. 18, 1942 2,318,843 Enos May 11, 1943 2,372,318 Enos Mar. 27, 1945 

